The roles of metal centers in biology will be explored on three fronts: 1) The bonding in non-heme iron-sulfur proteins will be investigated using laser Raman spectroscopy. The primary focus will be on plant ferredoxins, and on appropriate model compounds, for which new synthetic routes will be explored. The aim is to evaluate the extent of iron-iron and sulfur-sulfur bonding in these proteins, as an aid in elucidating the mechanism of electron transfer. 2) Interactions among apoferritin subunits and hydroxy-iron polymers will be examined, and the reconstitution of ferritin using trivalent iron sources will be attempted. Hydrolysis products in iron(III)-sugar systems will be characterized with the aim of understanding the effectiveness of sugars in biological transport of ferric iron. 3) The hypothesis that metal ions can activate phosphate transfer enzymes via bidentate coordination of the phosphate group, with formation of a strained four-membered ring, will be tested by preparing model compounds with bidentate phosphate derivatives, and performing kinetic studies. Synthesis and characterization of analogs of the presumed transition state in the bidentate mechanism will also be carried out.